On the specificity of the two forms of human serum alpha-L-fucosidase

All normal sera exhibiting either normal or low activities contain two forms of alpha-L-fucosidase (F1 and F2). These two forms, isolated from either type of serum, have respectively similar properties, but the low-activity sera contain a major proportion of the thermolabile, less-acidic form, F1. The specificities for natural substrates (glycoproteins and oligosaccharides) and for synthetic fucosides have been studied. All types of alpha-L-fucosidase linkages (1,2; 1,3; 1,4 and 1,6) are split by the form F2. The specificity of the form F1 is more restricted. Only alpha(1,3) and some types of alpha(1,2) and alpha(1,4) fucosyl linkages are split.